function getWindowHeight() {
    var windowHeight = 0;
    if (typeof(window.innerHeight) == 'number') {
        windowHeight = window.innerHeight;
    }
    else {
        if (document.documentElement && document.documentElement.clientHeight) {
            windowHeight = document.documentElement.clientHeight;
        }
        else {
            if (document.body && document.body.clientHeight) {
                windowHeight = document.body.clientHeight;
            }
        }
    }
    return windowHeight;
}





function refreshcoll() {
    if (document.getElementById) {
        var windowHeight = getWindowHeight();
        if (windowHeight > 0) {
            
            var contensElement = document.getElementById('contens');
            var contensHeight = contensElement.offsetHeight;
            var footerElement = document.getElementById('footer');
            var footerHeight  = footerElement.offsetHeight;
            var menuElement = document.getElementById('menu');
            var menuHeight  = menuElement.offsetHeight;
            var linksElement = document.getElementById('links');
            
            
            //alert('contensHeight = ' + contensHeight + '. footerHeight = ' + footerHeight + '. menuHeight = ' + menuHeight);
            
            //alert(windowHeight - (contensHeight + footerHeight + menuHeight));
            
            var veticalMargin = ((windowHeight - (contensHeight + footerHeight + menuHeight))/2)-75;
            
            if (veticalMargin >= 0) 
            { 
                                
                contensElement.style.top = veticalMargin + 'px';
                linksElement.style.top = veticalMargin + 'px';
                footerElement.style.top = windowHeight-footerHeight + 'px';
                
                //alert(document.getElementById('contens').style.top)
                
            }
            else             
            {
                contensElement.style.top = '0px';
                linksElement.style.top = ' 0px';;
                
                if(windowHeight-footerHeight >= 660){
                footerElement.style.top = windowHeight-footerHeight + 'px';                
                }
                else
                {
                footerElement.style.top = 660 + 'px';     
                }
            }
         
  
        }  
        
    }
}




window.onload = function() {
refreshcoll();

}


window.onresize = function() {
refreshcoll();

}